This invention relates generally to support apparatus for precision medical instruments, and more particularly to an adjustable support and stepping device for use with transrectal ultrasound imaging probes and a template grid or matrix used in brachytherapy for cancerous prostate and other transrectal ultrasound probe surgery.
The American Cancer Society estimated that there were 317,000 American men diagnosed with prostate cancer in 1997. Traditional treatment with radiation and surgery are associated with significant side effects and one currently widely applied and popular method for the treatment of prostate cancer is the percutaneous transperineal implantation of radioactive seeds of either Iodine-125 or Palladium-103 called brachytherapy. This procedure is performed with the patient in the lithotomy position, using an ultrasound imaging probe placed in the rectum to monitor seed placement. A template grid arrangement, which is kept in precise linear orientation with the ultrasound probe, must be accurately oriented adjacent to the perineum in relation to the prostate, and locked in position throughout the procedure to achieve optimum seed placement. Precise and reproducible orientation and positioning of the ultrasound imaging probe in the rectum is a key element in both the calculations required for determining the number and distribution of radioactive seeds required for treatment and their subsequent placement using preloaded needles guided by the perineal template and real time ultrasound imaging.
This form of treatment for prostate cancer has been increasing in popularity because of minimal patient morbidity compared to other available treatments and the potential for improved efficacy due to increasingly accurate methods of seed placement.
Presently, there are many homemade and commercially available devices for mounting, stepping and rotating the various commercially available transrectal ultrasound imaging probes designed for use in this procedure. None of these devices have achieved wide acclaim because of significant limitations in their ease of use and level of precision probe control and placement.
The present invention provides a template grid support or mount, and an ultrasound probe support with a stepping function for precision axial longitudinal movement and rotation of an ultrasound probe. Collectively, this invention is referred to as a stepper. During this procedure of brachytherapy, the ultrasound probe is manually inserted into the rectum and, once the desired orientation is achieved as viewed and confirmed by the monitored ultrasound images, the probe is connected to the stepper (which is typically attached to a support stand). Alternatively, if the support stand has suitable mobility, the stepper and probe can be attached to the support stand before insertion into the rectum. With the support stand set in a fixed mode, a range of positively controlled microadjustments available with some support stands may be used to achieve an ideal probe or instrument orientation for starting the procedure.
The template grid mount supports a needle guiding template grid which may be moved longitudinally along the centerline axis of the ultrasound probe while keeping a constant radial distance from this same axis. The stepping function allows precise, independent, and reproducible longitudinal movement of the ultrasound probe while keeping it in accurate radial position in relation to the grid. The rotation function of the stepper permits free axial rotation of the ultrasound probe and easy placement and removal of the ultrasound probe from the stepping device while retaining position of the stepping function and the template grid.
With a satisfactory starting image obtained, the stepper is used to guide the ultrasound probe and obtain transverse step section images. Seed implantation is achieved by passing seed containing needles through the template grid mounted on the template grid support. Direct ultrasound visualization of seed placement is achieved by utilizing the available movements of the stepper.